The invention relates to a conveyor belt system for transporting products through a bath of liquid, such as heated cooking oil in an oven or hot water in a boiler, comprising a feed belt, accommodated in a base frame, and a top belt, located above the feed belt and accommodated in an auxiliary frame, for transporting the products through the bath of liquid between the feed belt and the top belt, as well an adjustable support mechanism for adjusting the distance between feed belt and top belt, which support mechanism comprises further adjustable supports by means of which the auxiliary frame is supported on the base frame.
Conveyor belt systems of this type are known. They are used, for example, in ovens. The products, for example meat products such as hamburgers, chicken fillets, schnitzels or potato products and the like, move on the feed belt through the heated oil. Depending on the speed of the feed belt, they remain in the oil for a certain time in order to obtain the desired degree of cooking, browning and the like.
Some products are able to float in the oil and consequently no longer remain on the feed belt. As a consequence of this the residence time in the oil can no longer be controlled with the desired accuracy. However, by virtue of the top belt even such products can be fed through the oil in the desired, controlled manner. To this end, the top belt holds the products on the feed belt.
Since different types of products have different thicknesses, it must be possible to adjust the distance between the top belt and the feed belt. The support mechanisms must be adjusted for this purpose, which in practice is a time-consuming, high risk operation. First of all each support mechanism must be adjusted individually. Since there are usually 4 to 6 such support mechanisms, adjustment takes a great deal of time. Moreover, the adjustment mechanisms are located immediately alongside the bath containing hot oil. Therefore, the cover first has to be raised for adjustment. Adjustment then has to be carried out in the oil fumes being given off, which is unpleasant and can be dangerous.
The aim of the invention is to provide a conveyor belt system that does not have these disadvantages and can be operated more easily.
Said aim is achieved in that the supports are mechanically coupled to one another by coupling means for common adjustment thereof, for example by a central control element.
By mechanically coupling the supports, these can be operated simultaneously from one common control point. Rapid adjustment of the top belt is possible as a result.
The adjustable supports can be constructed in various ways, for example using a screw adjustment. However, the preference is for a construction where each support comprises a ramp mechanism, which ramp mechanisms are connected to one another by means of a pull element to provide relative movements in each ramp mechanism, which movements are associated with adjustment movements transverse to the base frame and auxiliary frame.
The ramp mechanisms may or may not be self-locking. The desired adjustment is always possible by means of the pull element; in the case of self-locking mechanisms a pull element is used that is able to exert a tensile force in two opposing directions.
Each ramp mechanism can comprise a ramp support and a block which can be moved with respect to one another, one of which is fixed with respect to one of the frames and the other is movably attached to a frame in order to provide adjustment movements.
Preferably at least two ramp mechanisms are provided on each longitudinal side of the frames, such that the slope of the ramp mechanisms on one longitudinal side is opposite to the slope of the ramp mechanisms on the other longitudinal side, which ramp mechanisms are connected to one another by a pull element that changes direction close to at least one transverse side of the frames.
There is then a winder close to the other transverse side of the frames, the pull element being a flexible cable or the like, the ends of which are each wound in the opposite direction on the winder.
According to a simple, stable embodiment, each ramp support is fixed to the base frame and each block is movably attached to the auxiliary frame.
With regard to the introduction of the products into the bath of liquid it can be desirable to position the first portion of the feed belt and the auxiliary belt at a certain slope. To this end the base frame and the auxiliary frame can each consist of a main frame component and a lead-in frame component hingeably connected thereto, the hinge pins of which are parallel to one another some distance apart, which lead-in frame components are mutually supported by at least two ramp mechanisms which are located on the two longitudinal sides thereof and are rigidly joined to one of the lead-in frame components and can be moved with respect to the other lead-in frame component.
In order in this embodiment also to be able to support the lead-in frame component of the auxiliary frame in the correct, adjustable manner, each ramp support of the lead-in frame components is fixed to, in each case, one of said components by means of a bearer which can be moved transversely with respect to said lead-in frame component and bears on the other lead-in frame component, and the associated block is movably attached to that lead-in frame component to which the bearer is also attached.
Preferably, the winder is accommodated on the main frame component to which the blocks are movably attached and the bearers are attached to the lead-in frame component associated with said main frame component, which lead-in frame component has deflection pulleys around which the cable changes direction.
The invention also relates to an oven comprising a conveyor belt system as described above, a tank to hold a quantity of cooking oil and a cover for covering the tank, the conveyor belt system being located in said tank.
According to the invention the drive for the coupling means can be located outside the tank or cover. It is now no longer necessary to lift the cover in order to adjust the auxiliary belt. This adjustment can therefore be carried out safely and rapidly.
Such an oven can be provided in the conventional manner with a lifting device for lifting the cover and the conveyor belt system relative to the tank. Recourse can be made to this lifting device should the adjustment forces become too high when adjusting the supports.
The invention therefore also relates to a method for operating such an oven in relation to adjustment of the distance between the feed belt and the top belt, comprising the following steps:
increasing the distance between the feed belt and the top belt by means of the lifting device,
adjusting the supports in order to obtain a new support position related to the new, desired distance between the feed belt and the top belt,
transferring the support of the top belt on the feed belt to the supports.